In the drilling and servicing of oil and gas wells, there are numerous operations that require a viscous fluid, such as the control of the loss of fluid from the fluid present in the borehole of the well to the surrounding subterranean formations contacted by the borehole, or the mixing of fluids within the borehole. Such operations include drilling, fracturing, gravel packing, workover, and other completion operations.
The present invention relates to the use of certain novel pills to control the fluid loss in such operations.